arXiv subjects

Ch. Baines

Publications and source records attributed to Ch. Baines.

3 recordsLinked to original sources

arXiv2012

Ordering in weakly coupled random singlet spin chains

The influence of bond randomness on long range magnetic ordering in the weakly coupled S = 1/2 antiferromagnetic spin chain materials Cu(py)2(Cl1-xBrx)2 is studied by muon spin rotation and bulk measurements. Disorder is found to have a strong effect on the ordering temperature TN, and an even stronger one on the saturation magnetization m0, but considerably more so in the effectively lower-dimensional Br-rich materials. The observed behavior is attributed to Random Singlet ground states of individual spin chains, but remains in contradiction with chain mean field theory predictions. In this context, we discuss the possibility of a universal distribution of ordered moments in the weakly coupled Random Singlet chains model.

cond-mat.str-el↗

arXiv2012

Direct observation of the quantum critical point in heavy fermion CeRhSi$_3$

We report on muon spin rotation studies of the noncentrosymmetric heavy fermion antiferromagnet CeRhSi$_3$. A drastic and monotonic suppression of the internal fields, at the lowest measured temperature, was observed upon an increase of external pressure. Our data suggest that the ordered moments are gradually quenched with increasing pressure, in a manner different from the pressure dependence of the Néel temperature. At $\unit{23.6}{kbar}$, the ordered magnetic moments are fully suppressed via a second-order phase transition, and $T_{\rm{N}}$ is zero. Thus, we directly observed the quantum critical point at $\unit{23.6}{kbar}$ hidden inside the superconducting phase of CeRhSi$_3$.

cond-mat.str-el↗

arXiv2004

Effect of two gaps on the flux lattice internal field distribution: evidence of two length scales from muSR in Mg1-xAlxB2

We have measured the transverse field muon spin precession in the flux lattice (FL) state of the two gap superconductor MgB2 and of the electron doped compounds Mg1-xAlxB2 in magnetic fields up to 2.8T. We show the effect of the two gaps on the internal field distribution in the FL, from which we determine two coherence length parameters and the doping dependence of the London penetration depth. This is an independent determination of the complex vortex structure already suggested by the STM observation of large vortices in a MgB2 single crystal. Our data agrees quantitatively with STM and we thus validate a new phenomenological model for the internal fields.

cond-mat.supr-con↗